possible Alternator issue?

Hey - in the last couple of weeks, my 75 Dart has been experiencing "power surges". I can be driving and all of a sudden, the headlights and heater fan will die for about 2 seconds and then it returns to normal. Sometimes the vehicle will almost stall but again, it comes back after a couple of seconds also. Any ideas???

Welcome aboard!

Possible poor connections? Battery terminals, Bulkhead connector, Ammeter?

Do the headlights and heater fan go out completely? Have you noticed other circuits having problems at the same time, or other indicators doing odd things? If so, how do they behave? And does it keep running OK some of the time?

We need some detail to be able to figure the likely issue. Could be something opening up or something shorting; so some further info will help.

If you have any idea how read a wiring diagram here is yours in this list of downloadabe links; it wil be good to use this so we can all work from the same page.

http://www.mymopar.com/index.php?pid=28

Check the thick wires (BATT & ALT) in your bulkhead connector. If melted (common), search "MAD Bypass" in the Electrical forum (where this question should be).

It wouldn't be your alternator, since your car could run fine for 100 miles on battery alone. But, buy a cigarette lighter voltmeter to monitor while driving ($15 Amazon, cheaper LED type at Harbor Freight).

good point^^^

nm9stheham said:

Do the headlights and heater fan go out completely? Have you noticed other circuits having problems at the same time, or other indicators doing odd things? If so, how do they behave? And does it keep running OK some of the time?

We need some detail to be able to figure the likely issue. Could be something opening up or something shorting; so some further info will help.

If you have any idea how read a wiring diagram here is yours in this list of downloadabe links; it wil be good to use this so we can all work from the same page.

http://www.mymopar.com/index.php?pid=28

Click to expand...

Yes, the heater fan and headlights go out completely. Sometimes it's a quick surge of a second or two and other times it's for 4 or 5 seconds. If I am driving on the highway, there isn't a noticeable power surge but if I am driving around 30mph, the car will hesitate as if it's going to stall. On a couple of occasions it's been hard to start. May take 4/5 cranks before it catches (that has happened twice after driving for about 15 miles). Thanks everyone for the feedback!!

nm9stheham said:

Do the headlights and heater fan go out completely? Have you noticed other circuits having problems at the same time, or other indicators doing odd things? If so, how do they behave? And does it keep running OK some of the time?

We need some detail to be able to figure the likely issue. Could be something opening up or something shorting; so some further info will help.

If you have any idea how read a wiring diagram here is yours in this list of downloadabe links; it wil be good to use this so we can all work from the same page.

http://www.mymopar.com/index.php?pid=28

Click to expand...

Should also mention that it first started happening after I had been on a road with a poor surface (lots of pot holes)....thinking something may have been jolted loose???

Hi,

You might want to check the bulk head connectors. I would disconnect them and look for burned contacts or melted plastic. If they look okay, try plugging them back in and unplugging them a few times to clean up the contact pins. If that solves the problem a little cleaning and dielectric grease might be in order

Well, if the headlights and blower go out completely, then it is not likely to be just the alternator as Bill said; the battery would simply pick up the loads in that case. In fact, it hardly sounds like the connection to the alternator through the firewall or to the battery through the firewall.

The headlights and blower are directly connected to the welded splice in the dash harness, which is directly connected to the alternator output through the bulkhead, and also to the battery through the bulkhead, fusible link, and wires to/from the starter relay's big lug.

The welded splice going bad is rare, so the most likley thing that comes to mind at this time is a short to ground (chassis) from a chafed wire. OP, take Bill's advice and get a voltmeter and put it in the lighter socket. If a short occurs, the voltage will likley dive down really low. Also, when it does this, look at your car's ammeter and see if there is a large deflection of the meter to the 'D' side.

BTW, a short on this main power circuit is pretty serious so take action on this ASAP. It may well be something else, but don't take a chance. The other symptoms reported (like occasional hard starting) need to wait and may or may not be related.